Vapor deposition apparatus, vapor deposition method and method of manufacturing organic el display apparatus

ABSTRACT

A vapor deposition apparatus disclosed by an embodiment comprises: a vacuum chamber ( 8 ); a mask holder ( 15 ) for holding a deposition mask  1 ; a substrate holder ( 29 ) for holding a substrate for vapor deposition ( 2 ); an electromagnet ( 3 ) disposed above a surface; a vapor deposition source  5  for vaporizing or sublimating a vapor deposition material; and a heat pipe ( 7 ) including at least a heat absorption part ( 71 ) and a heat dissipation part ( 72 ), the heat absorption part being in contact with the electromagnet ( 3 ), and the heat dissipation part being derived to an outside of the vacuum chamber ( 8 ). The heat pipe ( 7 ) and the electromagnet ( 3 ) are in intimate contact with each other at an area of a contact part between the heat pipe ( 7 ) and the electromagnet ( 3 ), the area being equal to or more than a cross-sectional area within an inner perimeter of a coil ( 32 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.15/757,420, having a 371(c) date of Jul. 29, 2018, which is a U.S.National Stage of PCT/JP2017/029814, filed on 21 Aug. 2017, the entiredisclosures of which are incorporated by reference.

TECHNICAL FIELD

The present invention relates to a vapor deposition apparatus, a vapordeposition method, and a method of manufacturing an organicelectro-luminescence (EL) display apparatus including a step ofvapor-depositing an organic layer.

BACKGROUND ART

For example, when an organic EL display apparatus is manufactured, adriving element, such as a thin-film-transistor (TFT), an electrode, andso on are formed on a supporting substrate, and organic layers aredeposited on the electrode disposed on the supporting substrate, foreach pixel. The organic layers are susceptible to moisture and thuscannot be etched. For this reason, the organic layers are deposited byoverlapping and arranging a deposition mask on the supporting substrate(substrate for vapor deposition), and vapor-depositing organic materialsthrough openings formed in the deposition mask. Consequently, necessaryorganic materials are deposited only on the electrodes of necessarypixels. The substrate for vapor deposition and the deposition mask mustbe positioned as close as possible. Otherwise, the organic layer couldnot be formed only on the accurate area of the pixel. If the organicmaterial is not deposited exclusively on the accurate area of the pixel,a displayed image is more likely to become unclear. As such, a magneticchuck is utilized to place the substrate for vapor deposition and adeposition mask close to each other by using a magnetic material as thedeposition mask and interposing the substrate for vapor depositionbetween a permanent magnet or an electromagnet and the deposition mask(for example, see Patent Document 1).

CITATION LIST Patent Literature

-   [PTL 1] JP 2008-024956 A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

Although a metal mask is conventionally used as the deposition mask, inorder to form a finer opening, a hybrid-type deposition mask tends to beused nowadays. The hybrid-type deposition mask is formed of a resinfilm, and a part of the resin film, excluding the peripheral edge of theopening, is supported by a metal support film. The deposition mask witha small amount of magnetic material, such as the hybrid mask, cannotsufficiently exhibit attraction unless it is under a strongermagnetizing field (magnetic field).

As mentioned above, with insufficient attraction, the accessibilitybetween the substrate for vapor deposition and the deposition mask wouldbe degraded. A strong magnetizing field is required in order tosufficiently close the deposition mask to the substrate for vapordeposition. When a permanent magnet is used as the magnet of themagnetic chuck, if its magnetizing field is strong, it is difficult toalign the substrate for vapor deposition and the deposition mask.Meanwhile, when an electromagnet is used, the magnetic field is almostset to zero by turning off the application of current to a coil of theelectromagnet, whereas the magnetic field can be generated and used forattraction by the application of current. Thus, at the time ofalignment, the magnetic field is not applied, and after alignment, themagnetizing field can be applied, which facilitates the alignmentbetween the substrate for vapor deposition and the deposition mask.

However, to generate a large magnetizing field using the electromagnet,it is necessary to increase the current. The strength of the magneticfield of the electromagnet is proportional to the product of the numberof turns of the coil of the electromagnet and the current flowingthrough the coil. For this reason, to increase a magnetic field, it isnecessary to raise the current or the number of turns. With eithermethod, the amount of heat generation is increased. An electrical wirehaving a small resistance is originally used for the coil of theelectromagnet because a large current is allowed to flow through thecoil of the electromagnet. Consequently, the electromagnet generatesheat due to a resistance loss of the current. Further, when a core (ironcore) is used for the electromagnet, the generated magnetic field can beincreased, but heat is generated by an eddy current. Therefore, when thecurrent is further increased in order to increase the generated magneticfield, the heat generation becomes more problematic.

Meanwhile, once heat generation occurs, the heat is transferred to thesubstrate for vapor deposition and the deposition mask, thus increasingtheir temperatures. The substrate for vapor deposition and thedeposition mask are made of different materials and hence have differentcoefficients of linear expansion. For example, when a difference in thecoefficient of linear expansion between the substrate for vapordeposition and the deposition mask is 3 ppm/° C., a difference inedge-to-edge size of them having 1 m length is 3 μm per degree Celsius(centigrade) in temperature. For example, assuming that the size of onepixel is 60 μm on one side (60 μm square), it is considered that only apixel displacement to about 15% is allowed at a resolution of 5.6 k.Thus, the pixel displacement is limited to 9 μm. In the above-mentionedexample, a temperature increase of 1° C. leads to a difference in sizeof 3 μm, and therefore the temperature increase is limited to 3° C. Thatis, the temperature increase in each of the substrate for vapordeposition and the deposition mask because of a temperature increase ofthe electromagnet needs to be suppressed to 3° C. or less. Meanwhile, asthe electromagnet is disposed in a vacuum chamber, it is difficult toradiate heat by air blowing or convection. It can be considered that theelectromagnet is water-cooled by winding a metal pipe around it andcausing a coolant to flow through the pipe. However, the heatdissipation through the coolant is time-consuming, so that a largeamount of heat generated cannot be sufficiently dissipated in a shorttime. In addition, if a joint is broken, there is a risk that a largeamount of water overflows into a vacuum chamber, potentially causingdamage to the vacuum chamber.

The present invention has been made to solve these problems, and it isan object of the present invention to provide a vapor depositionapparatus and a vapor deposition method which can easily performalignment between a substrate for vapor deposition and a deposition maskand attachment and detachment of the substrate for vapor depositionwhile surely and quickly cooling an electromagnet that generates heat,or suppressing the generated heat.

It is another object of the present invention to provide a method ofmanufacturing an organic EL display apparatus which exhibits excellentdisplay quality by using the above-mentioned vapor deposition method.

Means to Solve the Problem

A vapor deposition apparatus according to a first embodiment of thepresent invention comprises: a vacuum chamber; a mask holder for holdinga deposition mask disposed within the vacuum chamber; a substrate holderfor holding a substrate for vapor deposition in contact with thedeposition mask held by the mask holder; an electromagnet disposed on asurface, opposite to the deposition mask, of the substrate for vapordeposition held by the substrate holder; a vapor deposition sourceprovided facing the deposition mask to vaporize or sublimate a vapordeposition material; and a heat pipe including at least a heatabsorption part at a first end part thereof and a heat dissipation partat a second end part thereof opposite to the first end part, the heatabsorption part being provided in contact with the electromagnet, andthe heat dissipation part being derived to an outside of the vacuumchamber, wherein the heat pipe and the electromagnet are configured tobe joined together in intimate contact with each other at an area of acontact part between the heat pipe and the electromagnet, the area beingequal to or more than a cross-sectional area within an inner perimeterof a coil of the electromagnet.

A vapor deposition method according to a second embodiment of thepresent invention comprises: a step of superimposing an electromagnet, asubstrate for vapor deposition, and a deposition mask having a magneticmaterial, and attracting the deposition mask to the substrate for vapordeposition by energization of the electromagnet; and a step ofdepositing a vapor deposition material on the substrate for vapordeposition by vaporizing or sublimating the vapor deposition materialfrom a vapor deposition source disposed separately from the depositionmask, wherein the vapor deposition material is deposited while coolingthe electromagnet by using a heat pipe in intimate contact with theelectromagnet at an area wider than a cross-sectional area within aninner perimeter of a coil of the electromagnet.

A method of manufacturing an organic EL display apparatus according to athird embodiment of the present invention comprises: forming a supportsubstrate having at least a TFT and a first electrode; forming anorganic deposition layer by depositing organic materials on the supportsubstrate using the vapor deposition method mentioned above; and forminga second electrode on the organic deposition layer.

Effects of the Invention

The vapor deposition apparatus and the vapor deposition method accordingto the first and second embodiments of the present invention suppressthe temperature increase of the substrate for vapor deposition and thedeposition mask due to the heat generation in the electromagnet. Thus,the misalignment between the deposition mask and the substrate for vapordeposition due to thermal expansion is suppressed. As a result, theaccuracy of the vapor deposition of the organic layers is improved, sothat the vapor deposition with an accurate pattern can be performed. Byapplying these vapor deposition apparatus and the vapor depositionmethod to the manufacturing of the organic EL display apparatus, thedisplay apparatus with high definition can be obtained through formingfine pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a vapor deposition apparatusaccording to an embodiment of the present invention;

FIG. 2A is a diagram for explaining a structural example of a heat pipeshown in FIG. 1;

FIG. 2B is a diagram for explaining a modified example of the heat pipeshown in FIG. 1;

FIG. 3 is a diagram showing another example of a joint between anelectromagnet and the heat pipe;

FIG. 4 is a diagram showing still another example of a joint between theelectromagnet and the heat pipe;

FIG. 5A is a diagram showing yet another example of a joint between theelectromagnet and the heat pipe;

FIG. 5B is a cross-sectional view taken along line VB-VB of FIG. 5A;

FIG. 6A is a plan view of a heat pipe showing a further example of ajoint between the electromagnet and the heat pipe;

FIG. 6B is a cross-sectional view taken along line VIB-VIB of FIG. 6A;

FIG. 6C is a perspective view of the rolled heat pipe of FIG. 6A;

FIG. 6D is a diagram showing a state in which the heat pipe of FIG. 6Cis embedded in the core;

FIG. 7A is an explanatory diagram of a heat pipe for explaining a stillfurther example of a joint between the electromagnet and the heat pipe;

FIG. 7B is a plan view of a heat absorption part shown in FIG. 7A;

FIG. 7C is an explanatory diagram of a wick structure shown in FIG. 7B;

FIG. 7D is a schematic diagram showing a state in which the heat pipesshown in FIG. 7A are incorporated in a vapor deposition apparatus;

FIG. 8 is a diagram showing an example of a structure in which a heatpipe is connected to a vacuum chamber;

FIG. 9 is an enlarged view of an example of a deposition mask;

FIG. 10 is a diagram showing a vapor deposition process in the method ofmanufacturing an organic EL display apparatus according to the presentinvention; and

FIG. 11 is a diagram showing a state in which organic layers aredeposited in the method of manufacturing the organic EL displayapparatus of the present invention.

EMBODIMENT FOR CARRYING OUT THE INVENTION

Hereinafter, vapor deposition apparatuses and vapor deposition methodsaccording to first and second embodiments of the present invention willbe described with reference to the accompanying drawings. As illustratedin FIG. 1, the vapor deposition apparatus of the present embodimentincludes: a vacuum chamber 8; a mask holder 15 for holding a depositionmask 1 disposed in the vacuum chamber 8; a substrate holder 29 forholding a substrate for vapor deposition 2 in contact with thedeposition mask 1 held by the mask holder 15; electromagnets 3 disposedabove a surface, opposite to the deposition mask 1, of the substrate forvapor deposition 2 held by the substrate holder 29; a vapor depositionsource 5 provided facing the deposition mask 1 to vaporize or sublimatea vapor deposition material 51; and heat pipes 7, each including atleast a heat absorption part 71 at a first end part thereof and a heatdissipation part 72 at a second end part thereof opposite to the firstend part, the heat absorption part 71 being provided in contact with thecorresponding electromagnet 3, the heat dissipation part 72 beingderived to the outside of the vacuum chamber 8. The heat pipe 7 and theelectromagnet 3 are joined together in intimate contact with each otherat an area of a contact part between the heat pipe and the electromagnetthat is equal to or more than a cross-sectional area within an innerperimeter of a coil 32 in the electromagnet 3. It should be noted thatin FIG. 1, reference numeral 4 denotes a touch plate that cools thesubstrate for vapor deposition 2 and prevents deformation of thesubstrate for vapor deposition 2.

The electromagnet 3 as used herein means one in which the magnetic fieldis generated by energizing the coil 32 and lost by turning off theenergization. In a case where the electromagnet 3 includes a core(magnetic core or iron core) 31 inside the coil 32, the termelectromagnet 3 also implies the core 31. In a case where a yoke 33 isfurther attached to the core 31, the term electromagnet 3 also impliesthe yoke 33. In a case where the coil 32, the core 31, and the like areintegrated with a covering member 34 (see FIG. 3), such as a resin, theterm electromagnet 3 also implies the covering member 34. The heatabsorption part 71 of the heat pipe 7 refers to a contact part betweenthe heat pipe 7 and the electromagnet 3.

As shown in FIG. 1, the schematic structure of the vapor depositionapparatus adopts a magnetic chuck method to be described later, in whichthe deposition mask 1 and the substrate for vapor deposition 2 arearranged vertically (or horizontally) and side by side, and a magnet 3is disposed above the surface of the substrate for vapor deposition 2opposite to the deposition mask 1 in order to obtain the intimatecontact (good accessibility) between the deposition mask 1 and thesubstrate for vapor deposition 2, whereby the deposition mask 1 isattracted by the magnetic field of the magnet. In this case, a strongmagnetic field strongly attracts the deposition mask. However, when apermanent magnet is used as this magnet, the strong magnetic field actsat the time of alignment between the deposition mask 1 and the substratefor vapor deposition 2. Thus, the deposition mask 1 and the substratefor vapor deposition 2 are constantly attracted strongly together whenthey are placed close to each other. Consequently, there arises aproblem that it is difficult to perform precise alignment between thesubstrate for vapor deposition 2 and the deposition mask 1.

Meanwhile, when the electromagnet 3 is used as the magnet, the alignmentcan be performed in a state where no magnetic field is generated byturning off the current of the electromagnet 3 at the time of thealignment. As a result, the alignment can be performed easily. However,when a current flows through the electromagnet 3 to generate a magneticfield after the alignment, there arises a problem that the electromagnet3 generates heat. That is, the magnetic field generated by theelectromagnet 3 is proportional to the product of n and I (n·I) of thenumber of turns n of the coil 32 in the electromagnet 3 and the currentI flowing through the coil 32. Thus, to attract the deposition mask 1 bya sufficient magnetic field, it is necessary to increase the current Ior increase the number of turns n of the coil 32. When the number ofturns n of the coil 32 is increased, the electrical wire is made longer,and thereby an electric resistance R is increased. That is, the Jouleheat I²·R will increase, even if either the current I or the number ofturns n of the coil 32 is increased. Thus, the stronger the magneticfield, the more serious the problem of heat generation becomes.

For example, in the case of vapor deposition using a 1 m square (1 m×1m) deposition mask 1, to sufficiently attract the deposition mask 1, itis preferable to adopt a structure in which small electromagnets 3 (eachbeing hereinafter referred to as a unit electromagnet 3) are arrangedside by side as shown in FIG. 1, in terms of the uniformity of magneticforce distribution and the ease of heat dissipation. In this case, forexample, about 25 unit electromagnets 3, each unit having a core 31 of20 cm square, are arranged to cover the above-mentioned deposition mask1. In one unit electromagnet 3, an electrical wire having a length ofabout 100 m is wound around the core 31. When a copper wire(resistivity: 1.72×10⁻⁸ as Ω·m) having a diameter of about 1 mm is usedas the electrical wire (resistivity: 2.78×10⁻⁸Ω·m when a relativelyinexpensive aluminum wire is used), the resistance R of the electricalwire is about 2.2Ω in the length 100 m.

When a current per unit electromagnet 3 is 2 A, the amount of heatgenerated is I²·R=8.8 W. The deposition time for one substrate for vapordeposition 2 (energization time) is about 120 seconds, but when the unitelectromagnet 3 is continuously operated for 2 minutes, for example, anamount of heat of 8.8 W×120 s=1056 J (Joules) is generated. Thiscorresponds to 252 calories, leading to a temperature increase of about15° C. Since 25 unit electromagnets 3 are provided, the amount of heatgenerated is 6300 cal. Meanwhile, the volume (area) of the wholeelectromagnets 3 becomes larger, so that the temperatures of the wholeelectromagnets 3 are not 25 times higher than that of one unitelectromagnet 3. However, there is a mutual thermal action between theadjacent unit electromagnets 3, and further the temperature of the wholeelectromagnets 3 may also vary depending on the heat capacity of thesurroundings thereof, and the like, such as the presence or absence ofthe covering member 34. In addition, the vapor deposition iscontinuously performed by replacing the substrate for vapor deposition 2in practice. Consequently, as the electromagnets 3 are further heatedbefore being completely cooled, the heat is accumulated in theelectromagnets 3, leading to a further increase in temperature of thewhole electromagnet 3. In consideration of these factors, thetemperature of the whole electromagnets 3 is thought to increase up to amaximum of about 20° C. A temperature increase of the deposition mask 1and the like due to the temperature increase of the electromagnets 3 mayvary depending on various conditions. When the temperature increase ofthe electromagnet 3 is about 20° C., the temperature of each of thesubstrate for vapor deposition 2 and the deposition mask 1 is consideredto increase by about 12° C.

On the other hand, when the temperatures of the substrate for vapordeposition 2 or the deposition mask 1 increase, thermal expansionoccurs. However, the substrate for vapor deposition 2 and the depositionmask 1 are made of different materials and hence differ from each otherin thermal expansion. For example, even if the substrate for vapordeposition 2 is made of glass, and invar having a small expansion isused in a metal support film 12 (see FIG. 9) of the deposition mask 1, adifference in the coefficient of linear expansion between the substratefor vapor deposition 2 and the deposition mask 1 is about 3 ppm/° C.When a difference in coefficient of linear expansion between thesubstrate for vapor deposition 2 and the deposition mask 1 is 3 ppm/°C., a difference between one end and the other end of them 3 μm betweenthe substrate for vapor deposition and the deposition mask, when thedisplay panel has a length of 1 m. With an increase in size of thedisplay apparatus and an increase in definition, such as 4k or 8k, it isconsidered that the pixel displacement is limited to about 15% at aresolution of 5.6 k, for example. In the above-mentioned large-sizedscreen having one side of about 1 m, the size of each pixel is about 60μm on one side, and the pixel displacement of 15% corresponds to 9 μm.That is, a temperature increase of 3° C. is a limit for obtaining ahigh-definition image. As the temperature increase due to the heatradiation from the vapor deposition source 5 can be considered, thetemperature increase due to the electromagnets 3 must be avoided as muchas possible. In short, the present inventors have found that thetemperature increase of the deposition mask 1 due to the electromagnets3 must be suppressed to 10° C. or less at worst (when the resolution islow), preferably 5° C. or less, and more preferably 3° C. or less.

The size of the display panel is 1 m on one side in the above example,but generally, if one side of the display panel and one side of onepixel are proportional relation if the resolution is the same. Thereforethe sizes of these sides vary almost proportionally to each other. Forexample, if one side of 50 cm in the display panel is intended to havethe same resolution (in the above example, the resolution of 5.6 k) asone pixel, the length of one side of one pixel is 30 μm. Therefore, apixel displacement of 4.5 μm (15%) is allowed for the length of 50 cm.That is, as this shows that 4.5 μm/50 cm=9 ppm, when a difference incoefficient of linear expansion is 3 ppm/° C., the temperature increaseup to 3° C. is allowed. In short, this relationship can be applied toany sized display apparatus as long as the resolution is the same andthe allowable ratio of pixel displacement is the same. However, unlessthe resolution is required to be so high, for example, at the same levelof resolution as that of a current television, the pixel displacement upto about 40% is considered to be allowable. Therefore, the pixeldisplacement of about 25 μm is allowable for the panel of 1 m in length.That is, the present inventors have found that the heat dissipation fromthe electromagnet 3 needs to be done such that the temperature increaseof the deposition mask 1 due to the thermal conduction from theelectromagnets 3, which depends on the definition of the display panel,is 2° C. or less when the definition of about 8 k is required, 5° C. orless at a definition of about 4 k, and about 10° C. or less even at adefinition of a normal television or the like.

From that point of view, the present inventors have conceived ofemploying the heat pipe 7 because the cooling of the electromagnets 3 bywater cooling is insufficient, and the heat radiation cannot beperformed on the inside of the vacuum chamber 8 by blowing air orconvection. In this case, the heat pipe 7 can sufficiently cool itsenvironment at the ambient temperature, but in the vacuum vapordeposition apparatus, as shown in FIG. 1, the electromagnets 3, thesubstrate for vapor deposition 2, and the deposition mask 1 are disposedvery close to each other. As such, it is preferable to provide the heatpipe 7 in the vicinity of a surface of the electromagnet 3 facing thesubstrate for vapor deposition 2, but there is no space for arrangingthe heat pipe 7 having a normal rod shape. On the other hand, accordingto the heat pipe 7, the heat dissipation part 72 (see FIG. 1) isarranged outside the vacuum chamber 8, thereby making it possible todischarge heat generated by the electromagnet 3 to the outside of thevacuum chamber 8. Thus, a temperature increase inside the vacuum chamber8 can be efficiently suppressed. Accordingly, the use of the heat pipe 7is preferable.

Supposing that a space is provided for inserting the rod-shaped heatpipe 7, the distance between the electromagnet 3 and the deposition mask1 is increased. As a result, the magnetic field in the deposition mask 1is weakened, and thereby the attractive force is reduced. To secure themagnetic attraction force, it is necessary to further increase themagnetic field of the electromagnet 3, which requires increasing thecurrent, and consequently, heat is further generated. Therefore, if theheat pipe 7 is disposed away from the surface of the electromagnet 3facing the substrate for vapor deposition 2, almost all of the heatgenerated from the electromagnets 3 needs to be absorbed. Thus, thepresent inventors have found that how to dispose the heat pipe 7 becomesa very important issue when the heat pipe 7 is provided.

In order to solve such a problem, the present inventors have found, as aresult of intensive studies, that the temperature of an end surface ofthe electromagnet 3 facing the deposition mask 1 can be decreased bybringing the heat pipe 7 into contact with the electromagnet 3 across awide area, even on a surface of the electromagnet 3 opposite to thesurface thereof facing the deposition mask 1. Specifically, the presentinventors have found that the heat absorption part 71 of the heat pipe 7and the electromagnet 3 are brought into contact (intimate contact) witheach other at an area that is larger than at least a cross-sectionalarea within the inner perimeter of the coil 32 in the electromagnet 3.Thus, the temperature of the electromagnet 3 itself can decrease and thetemperature increase of the deposition mask 1 can be suppressed.

In other words, in particular, it is important to cool parts of the coil32 and the core 31 which generate heat, and it is effective to contactthe heat absorption part 71 of the heat pipe 7 with the heat generatingparts. That is, as mentioned above, for the purpose of preventing thetemperature increase of the substrate for vapor deposition 2 and thedeposition mask 1, it is preferable to decrease the temperature of theend surface of the electromagnet 3 facing the deposition mask 1.However, if there is no appropriate cooling means, it is necessary toreduce the temperature of the electromagnet 3 itself. In this case, asthe temperature of the coil 32 and the core 31 rises the most, it isimportant to decrease the temperature of these parts. Therefore, theheat absorption part 71 of the heat pipe 7 needs to be in contact withthe core 31 or the coil 32 of the electromagnet 3 over an area that isas wide as possible. That is, considering that the coil 32 is woundaround the outer perimeter of the core 31, the heat absorption part 71of the heat pipe 7 is preferably in contact with the core 31 or the core32 of the electromagnet, further at least the entire surface of the endsurface of the core 31 and further the cross-sectional area or morewithin the outer perimeter of the coil 32.

The reason why the heat absorption part of the heat pipe is in contactwith the electro magnet at the cross-sectional area within the innerperimeter of the coil 32 or at a larger area than this cross-sectionalarea is based on the fact that in order to obtain a strong magneticfield, the electromagnet 3 is usually provided with the core (magneticcore) 31, and the coil 32 is wound around the core 31. Therefore, thecross-sectional area within the inner perimeter of the coil 32 issubstantially equal to the cross-sectional area of the core 31. On theother hand, the heat generation of the electromagnet 3 includes heatgeneration of the coil 32 caused by the resistance loss of the coil 32,and heat generation caused by the resistance loss due to the eddycurrent generated in the core 31 when the core 31 is provided. As thecoil 32 is generally wound around the core 31, the coil 32 and the core31 are in intimate contact with each other, so that the heat generatedin the coil 32 is easily transferred to the core 31. For this reason,the present inventors have found that the generated heat can beefficiently dissipated by bringing the heat pipe 7 into contact with atleast the entire end surface of the core 31 to cool the core 31.Further, also in consideration of the contact with the coil 32generating heat, the contact area between the heat absorption part 71 ofthe heat pipe 7 and the electromagnet 3 is preferably equal to or largerthan the cross-sectional area within the outer perimeter of the coil 32.To enlarge the contact area, a part of the heat absorption part 71 ofthe heat pipe 7 is preferably embedded in the core 31. However when thecore 31 is excessively shaved, the magnetic field is weakened.

Meanwhile, the electromagnet 3 includes not only the coil 32 and thecore 31 as described above, but also the yoke 33, when the yoke 33 isconnected, for example, as shown in FIG. 1. Further, as shown in FIG. 3,when the core 31, the coil 32, the yoke 33, and the like are integratedtogether by the covering member 34, such as resin, the covering member34 and the like can also be regarded as a part of the electromagnet 3.Therefore, when the yoke 33 is connected as shown in FIG. 1, the widthof the yoke 33 is formed to be larger than the diameter of the core 31,so that the contact area can be increased without embedding a part ofthe heat absorption part 71 in the yoke 33 as shown in FIG. 1.

In addition, the coil 32, the core 31, and the like may be integratedtogether by the covering member 34, such as a resin (see FIG. 3), andthe heat absorption part 71 of the heat pipe 7 may be embedded in thecovering member 34. Further, a part of the heat absorption part 71 ofthe heat pipe 7 may be embedded in the core 31 or the yoke 33 (see FIGS.1 and 4). Alternatively, the heat absorption part 71 of each heat pipe 7is formed in a slender and elongated manner, so that the heat absorptionparts 71 can be inserted deeply in the core 31 with little influence onthe formation of a magnetic field (see FIGS. 5A and 5B). Furthermore, aheat absorption part 71 of the heat pipe 7 may be formed into a plateshape (flat shape) and then formed into a ring shape. The heatabsorption part 71 of such a ring-shaped heat pipe 7 may be embedded inthe core 31 (FIG. 6D). Moreover, as shown in Thermal Science &Engineering, pages 41-56, vol. 2, No. 3 (2015), a planar heat absorptionpart 71 of a loop-type heat pipe 7 may be provided on the end surface ofthe whole electromagnet 3 facing to the deposition mask 1 (FIGS. 7A to7D). In this case, only a plate-shaped heat absorption part 71 can beprovided in place of a touch plate 4 (see FIG. 1). That is, theplate-shaped heat absorption part 71 of the loop-type heat pipe 7 canonly cool the deposition mask, but also suppress the warpage of thesubstrate for vapor deposition 2.

The core 31 is made of iron or the like, and its thermal conduction isnot so good. Because of this, it is preferable that a coating layer 31 bmade of a material having a high thermal conductivity, such as copper,is formed on the surface of the core 31, at least in the vicinity of acontact part of the electromagnet with the heat pipe 7. By bringing theheat pipe 7 into intimate contact with the electromagnet 3 at an areathat is as wide as possible, the heat generated by the electromagnets 3can be efficiently discharged to the outside of the vacuum chamber 8. Amethod of increasing the contact area between the electromagnet 3 andthe heat pipe 7 will be described later.

(Structure of Heat Pipe)

As a typical example, the heat pipe 7 has a structure as shown in FIG.2A. That is, a wick 76 for moving a liquid by capillary action is formedon an inner wall of a vacuum-sealed pipe (case; container) 75 made of,for example, copper or the like, whereby a vacuum (low-pressure)structure is formed in which a small amount of an operating fluid (notshown) made of water or the like is sealed in the pipe 75. In thisstructure, when the heat absorption part 71, which is one end part, isheated by ambient heat, an operating fluid evaporates to generate vapor,thus increasing the internal pressure of the pipe 75. The vapor passesthrough a space 73 and is condensed and liquefied in the heatdissipation part (cooling part) 72, which is the other end part. Theliquefied liquid travels toward the heat absorption part 71 by thecapillary action in the wick 76 formed on the inner wall of the pipe 75.Owing to the latent heat transfer that accompanies such evaporation andthe condensation, a large amount of heat is transported from the heatabsorption part 71 to the heat dissipation part 72 even at a smalltemperature difference. The thermal conduction of the heat pipe 7 issaid to reach even 100 times the thermal conduction of a round copperrod. The wick 76 may have any structure in which a liquid travels due tothe capillary action, and may have a structure, such as a wire mesh, aporous body, a sponge, or the like.

As mentioned above, when the heat pipe 7 is disposed laterally, thecondensed liquid is conveyed to the heat absorption part 71 through thewick 76. Meanwhile, for example, when the heat pipe 7 is arranged in thevertical direction, and on its lower side, the heat absorption part 71is positioned (that is, a part of the heat pipe 7 having a hightemperature is disposed on the lower side of the heat pipe 7), theliquid is evaporated on the lower side to form a vapor, and the vaporrises and is condensed in the heat dissipation part 72. In this case,even without the wick 76, the liquefied liquid falls under its ownweight and returns to the heat absorption part 71. This is called athermosiphon type. In the present embodiment, either type of heat pipe 7can be used. For example, the wick 76 may be present when the heat pipe7 is arranged in a vertical direction.

FIG. 2B is a diagram showing a heat pipe 7 as another structuralexample. The heat pipe 7 is sealed with an operating fluid, such aswater. As described above, the heat pipe 7 is provided such that theheat absorption part 71 is in contact with the electromagnet 3. Thus,the heat pipe 7 is provided inside the vacuum chamber 8. If the heatpipe 7 is broken, the liquid sealed in its inside leaks into the insideof the vacuum chamber 8. If the liquid leaks into the vacuum chamber 8,the reliability and maintenance of the vacuum chamber become difficultto achieve.

A structure illustrated in FIG. 2B is to solve such a problem and isformed to have a double structure. That is, for example, an end of theheat absorption part 71 of a pipe 75 in the heat pipe 7 is configured ofa closing plate 77 and a flange portion 75 a, a protective pipe 78 isprovided on the flange portion 75 a by welding, brazing, or the like,and a space 79 is formed between the protective pipe 78 and the pipe(container) 75. This space 79 may be evacuated. With such a structure,even if the pipe (container) 75 is broken, the operating fluid does notleak into the vacuum chamber 8.

Further, the heat pipe 7 is not limited to the rod shape as shown inFIG. 2A, but may be formed in a flat shape (plate shape) as shown inFIGS. 6A and 6B described later. In this case, the pipe (container) 75can also be formed of a thin metal plate, synthetic resin, or the likethat can be subjected to a bending process, while having rigidity enoughto hold the space 73. Further, for example, a loop-type heat pipe 7 asshown in FIGS. 7A to 7C to be described later can be used. Such aloop-type heat pipe 7 is formed to have a very thin flat-shaped(plate-shaped) heat absorption part 71 of, for example, about 10 mm inthickness. Thus, the loop-type heat pipe 7 can be disposed at the frontsurface of each electromagnet 3, i.e., at the end surface of theelectromagnet 3, facing to the deposition mask 1. In this case, thetouch plate 4 shown in FIG. 1 may be omitted and replaced with the heatabsorption part 71 of the heat pipe 7. Consequently, the heat pipes 7can be disposed with little influence on the attractive force of theelectromagnets 3.

Next, a description will be given on an example in which the heat pipe 7and the electromagnet 3 are in contact with each other at a larger areathan the cross-sectional area within the inner perimeter of the coil 32.

First Example

In this first embodiment, as shown in FIG. 1, a unit electromagnet 3 isformed of a core 31, a coil 32 formed by winding an electrical wirearound the core 31, and a yoke 33 having a C-shaped cross section andconnected to an end part of the core 31 (an E-shaped yoke together withthe core 31). For example, a heat pipe 7 shown in FIG. 1 is provided soas to be connected to a back surface of the yoke 33 (a surface oppositeto the surface facing the deposition mask 1). When such a structure isadopted in which the heat pipe 7 is in contact with the yoke 33, thecontact area between the electromagnet and the heat pipe can be madelarger than the cross-sectional area within the inner perimeter of thecoil 32 by enlarging the diameter of the heat pipe 7.

In an example shown in FIG. 1, the heat absorption part 71 of the heatpipe 7 is disposed to be embedded in the yoke 33. It is not essentialthat a part of the heat absorption part 71 of the heat pipe 7 isembedded in the yoke 33. If an area of an end surface of the heat pipe 7is larger than the cross-sectional area within the inner perimeter ofthe coil 32, heat can be sufficiently dissipated. Nevertheless, asmentioned above, the larger the contact area between both the heat pipeand the electromagnet, the more preferable it is. That is, theelectromagnet is in contact with the heat pipe 7 not only at an area ofthe end surface of the heat pipe 7, but also at an area of a peripheralsurface of the embedded part of the heat pipe. With this structure, theheat dissipation effect of the electromagnet 3 is improved. Meanwhile,as the yoke 33 serves as a path for the magnetic field lines, if theheat absorption part 71 is embedded in the yoke 33 too deeply, themagnetic field lines are disturbed. However, such an influence can besuppressed by thickly forming the yoke 33 in advance.

Although not shown, a coating layer 31 b (see FIG. 4) having a highthermal conductivity is formed by copper plating or the like on thesurface of the core 31 or the surface of the yoke 33, thus furtherenhancing the heat dissipation effect. The heat pipe 7 has a thermalconductivity that is about 100 times higher than a thermal conductivityof copper, but as mentioned above, a space for effectively contactingthe heat pipe 7 with the electromagnet 3 is limited. For this reason, itis preferable to improve the thermal conduction within the electromagnet3 up to the heat pipe 7, which is arranged in a limited position.

The provision of the yoke 33 strengthens the magnetic field acting onthe deposition mask 1. Since a magnetic pole of the electromagnet 3 onits surface opposite to the surface facing the deposition mask 1 comesclose to the end surface facing the deposition mask 1 via the yoke 33,the magnetoresistance becomes smaller than that via the air, so that astrong magnetic field is obtained. Consequently, the current or thenumber of electromagnets 3 for obtaining the desired attractive forcecan be reduced, thereby further preventing the heat generation andsuppressing the temperature increase of the deposition mask 1 or thelike.

Second Example

In the configuration of a second example, as shown in FIG. 3, the coils32, the cores 31, and the yokes 33 are integrally covered with acovering member 34 made of a heat-resistant resin or the like, such asepoxy resin. The material for the covering member 34 is not limited tothis example, but is preferably a material that is less likely togenerate gas because the covering member is disposed inside the vacuumchamber 8. For example, PEEK (polyether ether ketone) or the like can beused. In particular, a material having good thermal conductivity ispreferable. A filler, such as metal powder, may be blended in thecovering member as needed.

In the example shown in FIG. 3, the heat absorption part 71 of each heatpipe 7 is attached to be in contact with the surface of the yoke 33.Even in this structure, the heat absorption part 71 of the heat pipe 7is embedded in the covering member 34, so that the side surface of theheat pipe 7 is also in contact with the electromagnet 3 (covering member34 and yoke 33). Therefore, the contact area between the heat pipe 7 andthe electromagnet 3 is sufficiently secured. In the example shown inFIG. 3, the heat pipe 7 is attached via the yoke 33, but the yoke 33 maynot be provided. Even if the yoke 33 is not provided, the side surfaceof the heat absorption part 71 of the heat pipe 7 is in contact with thecovering member 34, so that the contact area required for thermalconduction can be secured.

As shown in FIG. 3, by covering the cores 31 and the coils 32 of theelectromagnets 3 with the covering member 34, the contact areas with theheat pipes 7 can be easily increased, and in addition, heat generated bythe coils 32 can be directly transferred by the covering member 34. Thatis, the outer surface of the coil 32 has continuous mountain-shapedsurfaces because its outer surface is formed by winding the electricalwire having a circular cross section. Thus, even if the heat pipe 7 isintended to be directly contacted with the coil, a sufficient contactarea therebetween cannot be obtained. However, if the coils and heatpipes are covered with the covering member 34, such as resin, a gapbetween the wires of each coil 32 is filled with the covering member 34,whereby the contact with the coil 32 can be completely obtained. As aresult, heat generated in each coil 32 can be transferred to the heatpipe 7 directly via the covering member 34 without interposing the core31. Thus, the heat dissipation effect is improved significantly. In thiscase, it is considered that the heat generated in the coil 32 or thelike is covered with the covering member 34, so that the heat is notdirectly radiated and is more likely to be held. However, as theelectromagnets 3 are originally disposed inside the vacuum chamber 8,the heat dissipation by convection is hardly expected, and the heatdissipation effect due to conduction of the covering member 34 isthought to be larger than that exhibited by convection.

Third Example

FIG. 4 is a diagram showing a third example. In a structure of the thirdembodiment, a concave portion 31 a corresponding to the thickness andshape of the heat pipe 7 is formed in one end part of the core 31, andthe heat absorption part 71 of the heat pipe 7 is embedded in theconcave portion 31 a. With this structure, the area of an end part ofthe heat pipe 7 is smaller than the area within the outer perimeter ofthe core 31, that is, the inner perimeter of the coil 32. Nevertheless,as the heat absorption part 71 of the heat pipe 7 is embedded in thecore 31, the side surface of the heat pipe 7 also has a contact areawith the core, so that the contact area can be made larger than thecross-sectional area of the core 31.

A depth d of the concave portion 31 a is preferably larger from theviewpoint of increasing the contact area. However, if the concaveportion is too deep, the magnetoresistance of the magnetic field linespassing through the inside of the concave portion becomes large. Thus,as mentioned above, the concave portion is formed at the depth d thatmakes the contact area between the electromagnet 3 and the heat pipe 7larger than the cross-sectional area of the core 31. Specifically, thecontact area S1 between both the heat absorption part 71 and the core 31is expressed by S1=7πr²+2πrd, and the cross-sectional area of the core31, i.e., the cross-sectional area within an inner diameter of the coil32 is expressed as S2=πR² where r is a radius of the end surface of theheat absorption part 71 of the heat pipe 7, and R is a radius of thecross-sectional area of the core 31. Therefore, to achieve S1≥S2,(7πr²+27πrd)≥7R² is required. That is, it means d≥(R²−r²)/2r.

Like the example shown in FIG. 1, also, in this case, it is preferablethat especially the contact between the heat pipe 7 and theelectromagnet 3 (core 31) is good. For this reason, bonding ispreferably performed within the concave portion 31 a using an adhesivehaving good thermal conductivity, soldering, brazing, or the like.Furthermore, it is important to transfer heat of the core 31 or the liketo the heat pipe 7. Because of this, a coating layer 31 b having goodthermal conductivity, such as copper plating, is preferably formed. Sucha formation of the coating layer 31 b that has a larger thermalconductivity than the core 31 is not limited to the example shown inFIG. 4 and can be applied to other examples in the same manner. Even ifthe coating layer 31 b is not formed over the entire surface of the core31 or the like, the effect of the coating layer can be exhibited as longas this coating layer is formed in the vicinity of at least a jointedpart with the heat pipe 7.

Fourth Example

FIGS. 5A and 5B are diagrams for explaining a fourth example. That is,FIG. 5A is a side view, and FIG. 5B is a cross-sectional view takenalong the line VB-VB of FIG. 5A. In this example, the heat pipes 7 areslender and embedded in the cores 31. That is, if the cross-sectionalarea of the heat pipe 7 is reduced, the bad influence on the magneticfield lines is suppressed. Further, by lengthening the heat absorptionpart 71 of the heat pipe 7 and deeply embedding the heat absorption partin the core 31, the contact area between the heat pipe 7 and the core31, i.e., electromagnet 3 can be sufficiently increased. Thus, theslender heat pipe 7 is embedded in the core 31, thereby the temperatureof the core 31 can be efficiently decreased, while suppressing theinfluence on the magnetic field lines.

In a method of embedding the heat pipe 7 into the core 31, a hole havingthe same size as an outer diameter of the slender heat pipe 7 may beformed in the core 31, and the heat absorption part 71 of the heat pipe7 may be inserted into and bonded to the hole with an adhesive having alarge thermal conductivity, or may be bonded by soldering, brazing, orthe like, as mentioned above. Further, after inserting the heat pipe 7into the hole formed in the core 31, resin that contains fine particleshaving a large thermal conductivity, such as carbon nanotubes, may filla gap between the heat pipe 7 and the core 31. In this way, the thermalconductivity from the core 31 to the heat pipe 7 is improved. In anothermethod, sintering iron powder is placed in a molding die that has aconcave portion with a desired shape of the core 31, and the heat pipe 7is embedded in the molding die to pressurize the powder, followed bysintering. That is, the use of a so-called powder magnetic core formingmethod can also embed the heat pipe 7 in the core 31.

With this structure, the heat pipe 7 can be embedded to a sufficientdepth into the core 31 with little influence on the magnetic fieldlines. That is, the contact area between the heat pipe 7 and the core 31can be increased without reducing the cross-sectional area of the core31 so much. Further, by inserting the heat pipe 7 deep into the core 31,the temperature of the surface of the electromagnet 3 facing thedeposition mask 1 is more likely to be decreased. That is, as mentionedabove, there is no space between the electromagnet 3 and the depositionmask 1, into which a normal rod-shaped heat pipe 7 is inserted, from thenecessity to decrease an interval therebetween. Owing to this, the heatpipe 7 is inserted into or in contact with the core 31 from a surfaceopposite to the surface of the electromagnet 3 facing the depositionmask 1. Consequently, cooling of the core 31 is also performed from thesurface opposite to the surface of the electromagnet 3 facing to thedeposition mask 1. However, according to the present example, the heatpipe 7 can be positioned as close as possible to the surface of the core31 facing to the deposition mask 1. The heat pipe 7 can also be exposedat the front surface of the electromagnet 3 (surface facing thedeposition mask 1) through the core 31. In short, the surface of theelectromagnet 3 facing the deposition mask 1, which should be cooled themost, can be efficiently cooled.

Fifth Example

FIGS. 6A to 6D are diagrams for explaining a fifth example. That is, inthe fifth example, the heat pipe 7 is formed into a flat shape and thenrolled and embedded in the core 31. As illustrated in a plan view of theheat pipe 7 of FIG. 6A and in a cross-sectional view taken along theline VIB-VIB of FIG. 6B, in the fifth embodiment, the heat pipe 7 isformed in a tubular cuboid shape with each side being flat (plateshaped). In addition, this cuboid shape has one end part serving as theheat absorption part 71 and the other end part as the heat dissipationpart 72. The heat pipe 7 is different from the round bar shape shown inFIG. 2A, in that it has a flat shape, and is the same in that the wick76 is formed on the inner surface of the container (pipe) 75 and has thesame function. The wick 76 may not be provided as mentioned above aslong as the heat absorption part 71 is formed on the vertically lowerside and the heat dissipation part 72 is formed on the vertically upperside. The container 75 is formed of a flexible material, which does notdeform even when its internal pressure is set to a low pressure. Forexample, a thin copper plate, a stainless steel plate, or the likehaving a thickness of about 0.1 to 0.5 mm can be used.

The reason why the heat pipe has the flexibility is to roll the heatpipe as shown in a perspective view of FIG. 6C. By rolling the heat pipeas shown in FIG. 6C, a reduction in the cross-sectional area of the core31 can be minimized even if the heat pipe is embedded in the core 31, asschematically shown in FIG. 6D. That is, the influence on the magneticfield can be minimized. In FIG. 6D, the heat pipe 7 is schematicallyshown to be inserted only into an upper part of the core 31. However, inpractice, the heat pipe 7 can be inserted into a lower end part of thecore 31 (or a front surface of the electromagnet 3) or up to thevicinity thereof. In FIG. 6C, the rolled shape does not need to be aprecisely cylindrical shape, and may be a square shape or an indefiniteshape. In addition, the rolled ends may be joined, but do not need to bejoined with a gap therebetween. Reference numeral 74 denotes a sealingstopper made of copper or the like. As the heat dissipation part 72 isderived to the outside of the vacuum chamber 8, the heat dissipationpart 72 is hermetically sealed such that the vacuum inside the vacuumchamber 8 can be maintained.

In order to embed such a heat pipe 7 in the core 31, like theabove-mentioned the fourth example, a groove is formed in the core 31,and the rolled heat pipe 7 is inserted into the groove, which caneliminate a gap from the heat pipe. However, when the shape of therolled heat pipe 7 cannot be made constant, the configuration of thefifth example can be easily obtained by forming the core 31 using theabove-described formation method of a powder magnetic core, whichincludes compressing and molding the magnetic powder.

In the above-described example, the heat pipe 7 having a flat cuboidshape is rolled into a ring shape, but the heat pipe does not need to beformed into the ring shape. For example, heat pipes are formed such thatthe heat pipe 7 shown in FIG. 6A is divided into a plurality ofstrip-shaped heat pipes, each having the heat absorption part 71 and theheat dissipation part 72. Each of the strip-shaped heat pipes may beconfigured to be individually embedded in the corresponding core 31. Assuch, the heat pipe 7 can be embedded in the core 31 at a smallcross-sectional area along the shape of the core 31 without rolling theheat pipe 7. In this case, as the heat dissipation part 72 needs to bederived to the outside of the vacuum chamber 8, the use of a bellows tobe described later is required for fixing the heat pipe 7 to the vacuumchamber 8. However, even when replacing the substrate for vapordeposition 2 (see FIG. 1) or the deposition mask 1 (see FIG. 1) asmentioned later, the heat pipe 7 (for example, a part in the vicinity ofthe heat dissipation part 72) can be directly fixed and attached to thevacuum chamber 8 by performing the replacement while fixing theelectromagnet 3 (see FIG. 1).

According to this method, the heat pipe 7 is formed in a thin flatshape. Thus, even when the heat pipe 7 is embedded in the core 31, thecross-sectional area of the heat pipe 7 within the core 31 is small, andhence the influence on the magnetic field lines is very little. Inaddition, the influence on the magnetic field lines hardly changesdepending on the embedded depth. Therefore, the heat pipe 7 can beembedded in the core 31 almost across its entire height. As a result,the temperature of the surface of the electromagnet 3 facing to thedeposition mask 1 can be effectively decreased. That is, the heat pipe 7works very effectively to cool the electromagnet 3.

Sixth Example

FIGS. 7A to 7D are explanatory diagrams for a sixth example. The sixthexample has a structure similar to the loop-type heat pipe 7 describedin Thermal Science & Engineering, pages 41-56, vol. 2, No. 3 (2015),mentioned above. FIG. 7A shows a side view of the loop-type heat pipe 7;FIG. 7B shows a plan explanatory view of the heat absorption part 71;and FIG. 7C shows a structural example of a wick structure 80. That is,as shown in FIG. 7B, multiple (six in the example shown in FIG. 7B) wickstructures 80 are embedded in a case (container) 81 made of copper orthe like. Each wick structure 80 has a wick core 83 at its center part,as FIG. 7C shows the cross-sectional structure, a wick 82 is formed in agear-like shape around the wick core, and grooves 84 are formed betweenteeth of the wick 82 to provide a path for vapor.

The wick 82 can be formed to have the size of, for example, about 8 mm×9mm, (the thickness of the heat absorption part 71 can be reduced bycrushing it in the height direction into an oval shape). In this case,the groove 84 can be formed to have a depth of 1 mm and a width of about0.5 mm. The wick 82 and the wick core 83 are made of, for example, aporous material, such as PTFE (polytetrafluoroethylene). Pores in thisporous material can be formed with an average radius of about 5 μm and aporosity of about 35%. Such a wick 82 is formed integrally with thegrooves 84, for example, by molding a powdery PTFE.

In FIGS. 7A and 7B, reference numeral 86 denotes a vapor collectingportion, 87 denotes a vapor pipe, 88 denotes a liquid pipe, 89 denotes aliquid reservoir tank, 90 denotes a connection pipe, and 85 denotes aliquid distributing portion. The basic operation of this device is thesame as that of the heat pipe 7 shown in FIG. 2A described above, but inthis device, liquid is sucked by the capillary action of each wick core83 in the liquid distributing portion 85 to proceed from the wick core83 to the capillary of the wick 82, and is evaporated by the heat fromthe case 81. The evaporated vapor proceeds to a vapor collecting portion86 through spaces defined by the grooves 84. It should be noted that asshown in FIG. 7A, the grooves 84 are sealed by the wick 82 between thegrooves 84 and the liquid distributing portion 85, while the groove 84penetrates the vapor collecting portion 86. Thus, when the pressure inthe groove 84 increases due to evaporation of the liquid, the vaporadvances toward the vapor collecting portion 86. Then, the vapor iscooled in the heat dissipation part 72 through the vapor pipe 87 to beliquefied, and the resulting liquid is accumulated in the liquidreservoir tank 89 through the liquid pipe 88. The liquid stored in theliquid reservoir tank 89 returns to the liquid distributing portion 85via the connection pipe 90 by gravity. As the vapor is liquefied in theheat dissipation part 72, the pressure in the case 81 decreases, and theliquid further evaporates in the heat absorption part (evaporating part)71. The aforesaid processes are repeated. The heat absorption part(evaporating part) 71 is formed to have such a structure, thereby makingit possible to cool the wide area.

By using such a loop-type heat pipe 7, for example, as shown in FIG. 7D,the heat pipe 7 can be installed at the front surfaces (surfaces facingto the deposition mask 1) of the electromagnets 3 as it is. In theexample shown in FIG. 7D, the heat absorption part 71 of each heat pipe7 is provided in place of the touch plate 4 of the vapor depositionapparatus shown in FIG. 1. However, the conventional touch plate 4 maybe provided as it is, and the heat absorption part 71 of the loop-typeheat pipe may be inserted between the touch plate 4 and theelectromagnets 3. With such a structure, the surface of eachelectromagnet 3 facing the deposition mask 1 is cooled, which is themost appropriate for suppressing the temperature increase of thedeposition mask 1. In FIG. 7D, the same parts as those in FIG. 1 aredenoted by the same reference numerals, and for the description of theseparts, the following description with reference to FIG. 1 is used as asubstitute. Reference numeral 91 denotes a heat dissipation plate. Thatis, the heat dissipation part 72 can be cooled by air cooling or thelike.

In the loop-type heat pipe 7, the heat absorption part 71 is arrangedhorizontally and hence needs the wick 82 therein. However, theconnection pipe 90 leading from the liquid reservoir tank 89 to theliquid distributing portion 85 is disposed vertically, thus causing theliquid to drop under its weight, even if the wick is not provided. As aresult, the heat transfer is performed by circulation of the liquid andvapor between the evaporating part (heat absorption part 71) and theheat dissipation part 72. Thus, the temperature increase of thesubstrate for vapor deposition 2 and the deposition mask 1 can beefficiently suppressed.

(Schematic Structure of Vapor Deposition Apparatus)

As shown in FIG. 1 and described above, the vapor deposition apparatusaccording to one embodiment of the present invention is provided suchthat the mask holder 15 and the substrate holder 29 can be movedvertically to arrange the deposition mask 1 and the substrate for vapordeposition 2 close to each other within the vacuum chamber 8. Thesubstrate holder 29 is connected to a driving unit (not shown) so as tohold the peripheral edges of the substrate for vapor deposition 2 with aplurality of hook-shaped arms and to ascend and descend vertically. Inthe case of replacing the substrate for vapor deposition 2 or the like,the substrate for vapor deposition 2 carried into the vacuum chamber 8by robot arms is received by the hook-shaped arms, and the substrateholder 29 is descended until the substrate for vapor deposition 2approaches the deposition mask 1. An image pickup device (not shown) isalso provided for performing alignment. The touch plate 4 is supportedby a support frame 41, and connected, via the support frame 41, to adriving unit that descends the touch plate 4 until the touch plate 4comes into contact with the substrate for vapor deposition 2. Bydescending the touch plate 4, the substrate for vapor deposition 2 isplanarized.

The vapor deposition apparatus also includes a fine adjuster that movesthe substrate for vapor deposition 2 relative to the deposition mask 1while imaging alignment marks respectively formed on the deposition mask1 and the substrate for vapor deposition 2, when the deposition mask 1of the present embodiment is aligned with the substrate for vapordeposition 2. In order not to unnecessarily attract the deposition mask1 by the electromagnets 3, the alignment is performed in a state wherethe energization of the electromagnets 3 is stopped. Thereafter, thetouch plate 4 and the electromagnet 3 held by a similar holder (notshown) are descended, and current is caused to flow, whereby thedeposition mask 1 is attracted to the substrate for vapor deposition 2.

In the present embodiment, the heat pipe 7 is provided in intimatecontact with the yoke 33 of the electromagnet 3. As mentioned above, theheat absorption part 71 of the heat pipe 7 is in intimate contact withthe electromagnet 3 at the cross-sectional area within the innerdiameter of the coil 32, preferably, at an area larger than thecross-sectional area thereof, and the heat dissipation part 72 at theother end is derived to the outside of the vacuum chamber 8. The heatdissipation part 72 is placed in, for example, a heat discharge tank 95to enable cooling, such as air cooling or water cooling. In this way,the heat pipe 7 has the heat absorption part 71 at one end part thereofinside the vacuum chamber 8, and the heat dissipation part 72 at theother end part thereof outside the vacuum chamber 8. As described above,when replacing the substrate for vapor deposition 2 or the depositionmask 1, the electromagnet 3 or the like needs to be lifted upward anddescended again after the replacement. Because of this, the heat pipe 7cannot be directly fixed to a wall surface of the vacuum chamber 8. Insuch a case, as shown in FIG. 8, the heat pipe 7 is preferably fixed tothe vacuum chamber 8 via a bellows 96. The distance by which theelectromagnets 3 and the like are lifted when replacing the substratefor vapor deposition 2 or the like is about 100 mm or less, and thus thebellows 96 may be one that can expand and contract to that extent.

However, while the electromagnet 3 and/or the touch plate 4 may havefixed structure, the deposition mask 1 and the substrate for vapordeposition 2 may be descended to replace the substrate for vapordeposition 2 or the like, and then may be lifted and placed at apredetermined position. With such a structure, the heat pipe 7 can bedirectly bonded to and sealed on the vacuum chamber 8 without using thebellows 96. In the use of the bellows 96 described above, if the bellows96 is broken, the interior of the vacuum chamber 8 is exposed to theatmosphere, causing contamination of the inner wall. When the inner wallof the vacuum chamber 8 is contaminated, the inner wall needs to becleaned because the vacuum chamber 8 serves as a gas source. Owing tothis, the bellows 96 preferably has a double structure. For example, thestructure shown in FIG. 1 is preferably configured such that a spacebetween an outer wall of a heat discharge tank 95 and an outer wall ofthe vacuum chamber 8 is covered with a coating cover (not shown) toinclude the bellows 96. In this case, it is preferable that connectionparts between the heat pipe 7 and the heat discharge tank 95 and betweenthe heat discharge tank 95 and the coating cover, and between the vacuumchamber 8 and the coating cover are hermetically sealed, and the coatingcover has a flexible or bellows portion. This is because the heatdischarge tank 95 can also be moved by the movement of theelectromagnets 3. To evacuate the inside of the vacuum chamber 8, anexhaust device (not shown) is connected.

As mentioned above, various electromagnets, such as one having the core31, one having the yoke 33, and one having the covering member 34, canbe used as the electromagnet 3. The shape of the core 31 may be squareor circular. For example, when the size of the deposition mask 1 isabout 1.5 m×1.8 m, a plurality of electromagnets 3, each having a core31 (each electromagnet being referred to as a unit electromagnet), inwhich a cross-section of the unit electromagnet shown in FIG. 1 is about5 cm square, can be arranged side by side along with the size of thedeposition mask 1 as shown in FIG. 1 (the size thereof in the horizontaldirection is scaled down and the number of unit electromagnets is shownto be few in FIG. 1). Although the connection of the coils 32 is notshown in the example shown in FIG. 1, the coils 32 wound around therespective cores 31 are connected in series. However, the coils 32 ofthe respective unit electromagnets may be connected in parallel. Severalunits may be connected in series. A current may be independently appliedto a part of the unit electromagnet. The electromagnets 3 are cooled bythe method of the respective examples described above.

As shown in FIG. 9, the deposition mask 1 includes a resin film 11, ametal support film 12, and a frame (frame body) 14 formed around theresin film 11 and the metal support film 12. In the deposition mask 1,as shown in FIG. 1, the frame 14 is placed on the mask holder 15. Amagnetic material is used for the metal support film 12. As a result, anattractive force acts between the deposition mask 1 and the core 31 ofthe electromagnet 3 to attract the deposition mask 1 with the substratefor vapor deposition 2 sandwiched therebetween. The metal support film12 may be made of a ferromagnetic material. In this case, the metalsupport film 12 is magnetized by a strong magnetic field of theelectromagnets 3 (in a state where strong magnetization remains evenafter an external magnetic field is removed). When such a ferromagneticmaterial is used, the electromagnet 3 and the deposition mask 1 can beeasily separated from each other just by applying a current in theopposite orientation to the electromagnet 3 when intending to separatethe electromagnet 3 and the deposition mask 1 from each other. Even whena strong magnetic field for such magnetization is generated, the presentembodiment can suppress the heating of the electromagnet 3.

As the metal support film 12, for example, Fe, Co, Ni, Mn, or an alloythereof can be used. Among them, invar (an alloy of Fe and Ni) isparticularly preferable because this has a small difference in thecoefficient of linear expansion from the substrate for vapor deposition2 and hardly expands due to heat. The metal support film 12 is formed tohave a thickness of about 5 μm to 30 μm.

In FIG. 9, an opening 11 a of the resin film 11 and an opening 12 a ofthe metal support film 12 are tapered to become smaller toward thesubstrate for vapor deposition 2 (see FIG. 1). The reason for this is toprevent the evaporated vapor deposition material 51 from being blockedwhen the vapor deposition material 51 is vapor-deposited (see FIG. 1).It should be noted that various types of vapor deposition sources 5,such as a point-shaped, a linear-shaped, and a planer-shaped ones, canbe used as the vapor deposition source 5. For example, vapor depositionis performed on the entire surface of the substrate for vapor deposition2 by scanning at the paper surface of FIG. 1 from its left end to itsright end using a line-type vapor deposition source 5 (extending in adirection perpendicular to the paper surface of FIG. 1) in whichcrucibles are linearly arranged. Therefore, the above-mentioned taper isformed so that the vapor deposition material 51 evaporated from variousdirections and that even the vapor deposition material 51 coming from anoblique direction can reach the substrate for vapor deposition 2 withoutbeing blocked.

(Vapor Deposition Method)

Next, a vapor deposition method according to a second embodiment of thepresent invention will be described. As shown in FIG. 1 described above,the vapor deposition method in the second embodiment of the presentinvention includes: a step of overlaying the electromagnets 3, thesubstrate for vapor deposition 2, and the deposition mask 1 having amagnetic material and attracting the deposition mask 1 to the substratefor vapor deposition 2 by energization of the electromagnets 3; and astep of depositing the vapor deposition material 51 on the substrate forvapor deposition 2 by evaporating the vapor deposition material 51 fromthe vapor deposition source 5 disposed separately from the depositionmask 1, in which the vapor deposition material 51 is deposited whilecooling the electromagnets 3 by using a heat pipes 7 that is in intimatecontact with the electromagnets 3 at an area larger than thecross-sectional area within the inner perimeter of the coil 32 of theelectromagnet 3.

As mentioned above, the substrate for vapor deposition 2 is overlaid onthe deposition mask 1. The alignment between the substrate for vapordeposition 2 and the deposition mask 1 is performed as follows. Thealignment is performed by moving the substrate for vapor deposition 2relative to the deposition mask 1 while observing alignment marksrespectively formed on the deposition mask 1 and the substrate for vapordeposition 2 by means of the image pickup device. At this time, asmentioned above, in a state where the electromagnet 3 is not operated,the alignment can be performed by bringing the substrate for vapordeposition 2 and the deposition mask 1 close to each other. According tothis method, the opening 11 a of the deposition mask 1 can be alignedwith a corresponding vapor deposition position on the substrate forvapor deposition 2 (for example, a pattern of a first electrode 22 on asupport substrate 21, in the case of an organic EL display apparatus tobe described later). After the alignment, the electromagnets 3 areoperated. Consequently, the strong attractive force acts between theelectromagnets 3 and the deposition mask 1, thereby surely bringing thesubstrate for vapor deposition 2 and the deposition mask 1 close to eachother. At this time, the coil 32 of each electromagnet 3 generates heatby causing a current to flow therethrough. However, as mentioned above,since the heat pipe 7 is connected to the electromagnet 3, the generatedheat can be efficiently dissipated, so that the heat transfer to thedeposition mask 1 hardly occurs, which suppresses a temperature increaseof the deposition mask 1.

Thereafter, as shown in FIG. 1, the vapor deposition material 51 isdeposited on the substrate for vapor deposition 2 by flying(vaporization or sublimation) the vapor deposition material 51 from thevapor deposition source 5 which is disposed separately from thedeposition mask 1. Specifically, as mentioned above, line source formedby crucibles or the like arranged linearly is used, but the presentinvention is not limited thereto. For example, in the case ofmanufacturing an organic EL display apparatus, a plurality of types ofdeposition masks 1, each having openings 11 a formed for some pixels, isprepared. Then, a vapor deposition process is repeatedly performed amultiple number of times by replacing one deposition mask 1 with anotherto thereby form organic layers.

According to this vapor deposition method, vapor deposition is performedwhile cooling the electromagnets 3 with the heat pipes 7. As a result, arelative misalignment between the deposition mask 1 and the substratefor vapor deposition 2 is suppressed, so that vapor deposition isperformed with excellent accuracy. It is preferable that when a currentinto the electromagnet 3 is turned on and off, the rise and fall of thecurrent become gentle from the viewpoint of suppressing the occurrenceof electromagnetic induction. For example, it is preferable that acapacitor is connected in parallel with the electromagnet 3; that aterminal is provided at some midpoint in the coil 32 and then a part tobe energized in the coil 32 is gradually enlarged; or that areverse-wound part is formed in the coil 32, this part offset agenerated magnetic field when the current to the electromagnet 3 isturned on or off, and a current flowing through the reverse coil part isgradually turned off after the current to the electromagnet 3 is turnedon or off.

(Method of Manufacturing Organic EL Display Apparatus)

Next, a method of manufacturing an organic EL display apparatus usingthe vapor deposition method of the above embodiment will be described.Any processes in the manufacturing method other than the vapordeposition method can be performed by the well-known methods. Thus, amethod of depositing organic layers by the vapor deposition method ofthe present invention will be mainly described with reference to FIGS.10 and 11.

A method of manufacturing an organic EL display apparatus according to athird embodiment of the present invention includes: forming a TFT (notshown), a planarizing layer, and a first electrode (for example, ananode) 22 on the support substrate 21; aligning and overlaying thedeposition mask 1 on one surface thereof; and forming an organicdeposition layer 25 by using the above-described vapor deposition methodto deposit the vapor deposition material 51. A second electrode 26 (seeFIG. 11; a cathode) is formed on the organic deposition layer 25.

For example, although not shown completely, a driving element, such as aTFT, is formed on the support substrate 21, such as a glass plate, foreach of RGB sub-pixels in each pixel, and the first electrode 22connected to the driving element is formed, on the planarizing layer, bya combination of a metal layer made of Ag, APC, etc., and an ITO layer.As shown in FIGS. and 11, insulating banks 23 made of SiO₂, an acrylicresin, a polyimide resin, or the like are formed between the sub-pixelsto isolate the sub-pixels from each other. The above-mentioneddeposition mask 1 is aligned with and fixed on such insulating banks 23on the support substrate 21. As shown in FIG. 1 described above, thefixing is performed by, for example, using the electromagnet 3, which isprovided via a touch plate 4 on a surface opposite to the vapordeposition surface of the support substrate 21 (substrate for vapordeposition 2), to attract the deposition mask 1. As mentioned above,since the magnetic material is used as the metal support film 12 of thedeposition mask 1 (see FIG. 9), the metal support film 12 of thedeposition mask 1 is magnetized when a magnetic field is applied theretoby the electromagnet 3, thereby generating the attractive force betweenthe core 31 and the metal support film. Even when the electromagnet 3does not have the core 31, the deposition mask 1 is attracted to theelectromagnets 3 by a magnetic field generated by a current flowingthrough the coil 32. At this time, as described above, the heatgenerated by the flowing current is rapidly transferred to anddissipated in the heat dissipation part 72 of the heat pipe 7. As aresult, even if there is a difference in the coefficient of thermalexpansion between the deposition mask 1 and the support substrate 21,the relative misalignment therebetween is significantly suppressed. Inaddition, the high-definition organic EL display apparatus can beobtained.

In this state, as shown in FIG. 10, the vapor deposition material 51 isevaporated from the vapor deposition source (crucible) 5 in the vapordeposition apparatus, and then the vapor deposition material 51 isdeposited only on parts of the support substrate 21 exposed from theopenings 11 a of the deposition mask 1, so that the organic depositionlayer 25 is formed on the first electrode 22 in each of desiredsub-pixels. This vapor deposition step may be performed on eachsub-pixel by sequentially replacing one deposition mask 1 with another.Alternatively, the deposition mask 1 through which the same material isdeposited concurrently on the plurality of sub-pixels may be used. Whenreplacing the deposition mask 1, a power supply circuit (not shown) isturned off so as to remove a magnetic field applied to the metal supportfilm 12 (see FIG. 9) of the deposition mask 1 through the electromagnets3 (see FIG. 1), which is not shown in FIG. 10. Also at this time, theheat pipes 7 still act to transfer the whole heat remaining in theelectromagnets 3 to the heat dissipation parts 72.

FIGS. 10 and 11 simply show that the organic deposition layer 25 isshown by a single layer, but the organic deposition layer 25 may beformed of a plurality of layers made of different organic materials. Forexample, a hole injection layer is provided as a layer in contact withthe anode 22 in some cases. The hole injection layer improves a holeinjection property and is made of materials having a good ionizationenergy matching. A hole transport layer which is made of, for example,an amine-based material, is provided on the hole injection layer. Thehole transport layer improves stable transportability of holes andenables confinement of electrons (energy barrier) into a light emittinglayer. Further, the light emitting layer, which is selected depending onemission wavelength to be emitted, is formed on the hole transportlayer, for example, by doping red or green organic phosphor materialinto Alq₃, for the red or green wavelength. As a blue-based material, abis(styryl)amine (DSA)-based organic material is used. An electrontransport layer is formed of Alq₃ or the like on the light emittinglayer. The electron transport layer improves an electron injectionproperty and stably transports electrons. These respective layers, eachhaving a thickness of about several tens of nm, are deposited to formthe organic deposition layer 25. It should be noted that an electroninjection layer, such as LiF or Liq, which improves the electroninjection property, may also be provided between the organic layers andthe metal electrode. In the present embodiment, these layers areincluded in the organic deposition layer 25.

In the organic deposition layer 25, an organic layer of a materialcorresponding to each color of RGB is deposited as the light emittinglayer. In addition, the hole transport layer, the electron transportlayer, and the like are preferably deposited separately by usingmaterials suitable for the light emitting layer, if emphasis is placedon light emission performance. However, in consideration of the materialcost, the same material common to two or three colors of RGB isdeposited in some cases. In a case where the material common tosub-pixels of two or more colors is deposited, the deposition mask 1 isformed to have openings 11 a formed in the sub-pixels sharing the commonmaterial. In a case where individual sub-pixels have different depositedlayers, for example, one deposition mask 1 is used for sub-pixels of R,so that the respective organic layers can be sequentially deposited. Ina case where an organic layer common to RGB is deposited, other organiclayers for the respective sub-pixels are deposited up to the lower sideof the common layer, and then at the stage of the common organic layer,the common organic layer is deposited across the entire pixels at onetime using the deposition mask 1 with the openings 11 a formed in RGBsites. In the case of mass production, a number of vacuum chambers 8 ofthe vapor deposition apparatuses may be arranged side by side, differentdeposition masks 1 may be mounted in the respective vacuum chambers 8,and the support substrate 21 (substrate for vapor deposition 2) may bemoved to each vapor deposition apparatus to continuously perform vapordeposition.

After finishing the formation of the deposition layer of all the organiclayers including the electron injection layer, such as a LiF layer, theelectromagnets 3 are turned off, and then these electromagnet 3 areremoved from the deposition mask 1 as mentioned above. Thereafter, asecond electrode (e.g., a cathode) 26 is formed over the entire surface.An example shown in FIG. 11 is a a top emission type, in which light isemitted from a surface opposite to the support substrate 21 shown in thefigure. Thus, the second electrode 26 is formed of a light-transmissivematerial, for example, a thin Mg—Ag eutectic layer. Alternatively, Al orthe like can be used. It should be noted that in a bottom emission typewhich emits light through the support substrate 21, ITO, In₃O₄, or thelike can be used for the first electrode 22, and metals having low workfunctions, for example, Mg, K, Li, Al, or the like, can be used for thesecond electrode 26. A protective film 27 made of, for example, Si₃N₄ orthe like, is formed on the surface of the second electrode 26. It shouldbe noted that the whole laminated body is sealed by a sealing layer madeof glass, a moisture-resistant resin film, or the like (not shown), andis thus configured to prevent the organic deposition layer 25 fromabsorbing moisture.

Alternatively, a structure can also be provided in which the organiclayers may be made common or shared as much as possible, and a colorfilter may be provided on the surface of the organic deposition layer.

(Summary)

(1) A vapor deposition apparatus according to the first embodiment ofthe present invention comprises: a vacuum chamber; a mask holder forholding a deposition mask disposed within the vacuum chamber; asubstrate holder for holding a substrate for vapor deposition in contactwith the deposition mask held by the mask holder; an electromagnetdisposed on a surface, opposite to the deposition mask, of the substratefor vapor deposition held by the substrate holder; a vapor depositionsource provided facing the deposition mask to vaporize or sublimate avapor deposition material; and a heat pipe including at least a heatabsorption part at a first end part thereof and a heat dissipation partat a second end part thereof opposite to the first end part, the heatabsorption part being provided in contact with the electromagnet, andthe heat dissipation part being derived to an outside of the vacuumchamber, wherein the heat pipe and the electromagnet are configured tobe joined together in intimate contact with each other at an area of acontact part between the heat pipe and the electromagnet, the area beingequal to or more than a cross-sectional area within an inner perimeterof a coil of the electromagnet.

According to the vapor deposition apparatus of the embodiment of thepresent invention, the heat absorption part of the heat pipe is providedto be in contact with the electromagnet of the vapor depositionapparatus at an area equal to or more than the cross-sectional areawithin the inner perimeter of the coil of the electromagnet.Consequently, heat generated in the electromagnet can be dissipatedquickly. That is, even if the heat absorption part of the heat pipe isin contact with the surface of the electromagnet opposite to the surfacethereof facing the deposition mask, the heat pipe is in contact with theelectromagnet in a wide range of the heat absorption part of the heatpipe, thereby achieving the heat dissipation across the entireelectromagnet. As a result, this suppresses an increase in thetemperature of the substrate for vapor deposition and the depositionmask due to the heat transferred from the electromagnet to the substratefor vapor deposition and the deposition mask. In this way, the alignmentbetween the substrate for vapor deposition and the deposition mask dueto an increase in the temperature thereof is suppressed, so that thevapor deposition material is deposited on the accurate position of thesubstrate for vapor deposition with an accurate pattern. Therefore, thehigh-definition display panel can be obtained.

(2) It is preferable that the electromagnet and the heat pipe are incontact with each other such that a temperature increase of thedeposition mask due to the electromagnet is 10° C. or less. That is, asthe contact area between the heat absorption part of the heat pipe andthe electromagnet becomes larger, the temperature increase of theelectromagnet is suppressed more, and the temperature increase of thesubstrate for vapor deposition and the deposition mask is alsosuppressed more.

(3) It is preferable that the electromagnet includes a columnar core,and a yoke is attached to one end part of the core, thereby forming anE-shaped yoke in which a cross-sectional shape including the core is anE shape, and the heat pipe is in intimate contact with the E-shapedyoke. By providing such a yoke, the contact area of the heat absorptionpart of the heat pipe with the electromagnet (yoke) can become larger,as well as strengthening the magnetic field in the vicinity of thedeposition mask.

(4) It is preferable that the electromagnet comprises a covering memberfor integrating a columnar core and the coil formed by winding anelectrical wire around the core, and the heat absorption part of theheat pipe is formed so as to be in intimate contact with the coveringmember. Although the covering of the electromagnet with the coveringmember restricts the heat dissipation through the radiation, since theelectromagnet is originally disposed within the vacuum chamber, the heatdissipation effect through the radiation is slight. On the other hand,by covering with the covering member, the heat transfer due toconduction is obtained, and by embedding the heat absorption part of theheat pipe in the covering member, the heat dissipation effect is morelikely to be obtained very effectively. In this case, the coveringmember is preferably made of material having a large thermalconductivity. By covering with such a covering member, this coveringmember is sufficiently in contact with the surroundings of theelectrical wire (coil), which tends to generate heat the most.Consequently, the heat dissipation effect due to the thermal conductionis very significant.

(5) It is preferable that the electromagnet comprises a columnar core,and the heat absorption part of the heat pipe is embedded in the core upto a depth of ½ or more of a length of the core. It is the mostpreferable that the temperature increase of, especially, the surface(front surface) of the electromagnet facing the substrate for vapordeposition is suppressed. However, there are many cases in which theheat pipe must be in contact with the backside which is an oppositesurface to the front surface of the electromagnet due to a limitedspace. Even in these cases, the temperature of the front surface of theelectromagnet can be decreased by embedding the heat pipe up to a depthof a half or more of the core. The deeper the embedding depth is, themore preferable it is. The embedding depth is further preferably ⅔ ormore of the core, or the extent that the heat pipe is exposed at thefront surface of the core.

(6) It is preferable that the heat pipe is formed in a flat shape andthen rolled in a ring shape to form a cylindrical body, and the heatabsorption part of the cylindrical body is embedded in the core. Theelectromagnet with the core obtains a stronger magnetic field than anelectromagnet with an air core. Therefore, it is not preferable to forma hole in the core from the viewpoint of the magnetic field. However,the hole extending in the axis direction does not vary influence on themagnetic field regardless of its depth. Therefore, the insertion of theheat absorption part of the heat pipe into the deep hole at a smallcross-sectional area is preferable because the heat dissipation canbecome significant without weakening the magnetic field so much.

(7) It is preferable that the electromagnet comprises a columnar core,and a coating layer having a larger thermal conductivity than that ofthe core is formed on a vicinity of at least a contact part of theelectromagnet with the heat pipe. As mentioned above, it is difficult toprovide the heat pipe at the front surface of the electromagnet due tothe limited space, and hence the heat pipe is placed in contact with thebackside of the electromagnet in many cases. However, the thermalconductivity of iron forming the core is not excellent so much. Becauseof this, a coating layer with excellent thermal conductivity, such as acopper plating, is preferably formed in order to improve the thermalconductivity of the core. The formation of the coating layer ispreferable positioned across the entire surface of the core includingthe concave portion (also including a yoke in a case where the yoke isprovided). It is considered that the thermal conduction of heat from thecore to the heat pipe is improved by forming the coating layer on atleast the contact part between the electromagnet and the heat absorptionpart of the heat pipe.

(8) It is preferable that the heat absorption part of the heat pipe isformed in a planar shape, and the heat absorption part of the heat pipeis disposed in intimate contact with a surface of the electromagnetfacing to the deposition mask. With this structure, the heat pipe has aspecial structure, and thereby only the heat absorption part of the heatpipe can be in contact with the front surface of the electromagnet. As aresult, this is very preferable because the surface of the electromagnetfacing to the deposition mask can be cooled.

(9) The heat pipe is connected to the vacuum chamber via a bellows. Withsuch a structure, the electromagnet can be ascended and descendedtogether with the substrate holder or the like.

(10) It is preferable that a second chamber covering the vacuum chamberis formed at an outer perimeter of the vacuum chamber, and a spacebetween the vacuum chamber and the second chamber is set at a degree ofvacuum lower than a degree of vacuum of an inside of the vacuum chamber.Even if the bellows is broken, the inside of the vacuum chamber can besuppressed from being contaminated by the atmosphere.

(11) It is preferable that a protective pipe for preventing leakage of aliquid from the heat pipe due to break of the heat pipe is formed at anouter perimeter of the heat pipe. Even if the heat pipe is broken, theinside of the vacuum chamber can be suppressed from being contaminatedwith liquid sealed in the heat pipe.

(12) A vapor deposition method according to the second embodiment of thepresent invention comprises a step of superimposing an electromagnet, asubstrate for vapor deposition, and a deposition mask having a magneticmaterial, and attracting the deposition mask to the substrate for vapordeposition by energization of the electromagnet; and a step ofdepositing a vapor deposition material on the substrate for vapordeposition by vaporizing or sublimating the vapor deposition materialfrom a vapor deposition source disposed separately from the depositionmask, wherein the vapor deposition material is deposited while coolingthe electromagnet by using a heat pipe in intimate contact with theelectromagnet at an area wider than a cross-sectional area within aninner perimeter of a coil of the electromagnet.

According to the vapor deposition method of the second embodiment of theprevent invention, the heat pipe is in intimate contact with theelectromagnet at an area wider than the cross-sectional area within theinner perimeter of the coil in the electromagnet. Thus, even if thedeposition mask is attracted by the electromagnet during the vapordeposition, the temperature increase of the electromagnet is suppressed.Furthermore, the temperature increase of the substrate for vapordeposition and the deposition mask are also suppressed. As a result, themisalignment between the substrate for vapor deposition and thedeposition mask due to the thermal expansion can be suppressed, makingit possible to perform the vapor deposition with good accuracy.

(13) It is preferable that the electromagnet is cooled such that atemperature increase of the deposition mask due to the electromagnet is10° C. or less. The temperature increase of the electromagnet issuppressed, and as a result, the temperature increase of the depositionmask is reduced to 10° c. or less, whereby a displacement of thedeposition layer made of the vapor deposition material with respect tothe pixel is suppressed within an allowable range, thereby obtaining thehigh-accuracy deposited film.

(14) Further, a method of manufacturing an organic EL display apparatusaccording the third embodiment of the present invention comprises:forming a support substrate having at least a TFT and a first electrode;forming an organic deposition layer by depositing organic materials onthe support substrate using the vapor deposition method according toclaim 12 or 13; and forming a second electrode on the organic depositionlayer.

According to the method of manufacturing an organic EL display apparatusof the third embodiment in the present invention, the heat release fromthe electromagnet is suppressed when manufacturing the organic ELdisplay apparatus, which suppresses the misalignment between thesubstrate for vapor deposition and the deposition mask, therebyobtaining the display panel with high definition.

REFERENCE SIGNS LIST

-   1 Deposition mask-   2 Substrate for vapor deposition-   3 Electromagnet-   4 Touch plate-   5 Vapor deposition source-   7 Heat pipe-   8 Vacuum chamber-   12 Metal support film-   15 Mask holder-   21 Support substrate-   22 First electrode-   23 Insulating bank-   25 Organic deposition layer-   26 Second electrode-   29 Substrate holder-   31 Core (magnetic core)-   31 b Coating layer-   32 Coil-   33 Yoke-   34 Covering member-   41 Support frame-   51 Vapor deposition material-   71 Heat absorption part-   72 Heat dissipation part-   73 Space-   78 Protective pipe-   80 Wick structure-   81 Case (container)-   82 Wick-   83 Wick core-   84 Groove-   96 Bellows

1. A vapor deposition apparatus, comprising: a vacuum chamber; a maskholder for holding a deposition mask disposed within the vacuum chamber;a substrate holder for holding a substrate for vapor deposition incontact with the deposition mask held by the mask holder; anelectromagnet disposed above a surface, opposite to the deposition mask,of the substrate for vapor deposition held by the substrate holder; avapor deposition source provided facing the deposition mask to vaporizeor sublimate a vapor deposition material; and a heat pipe including atleast a heat absorption part at a first end part thereof and a heatdissipation part at a second end part thereof opposite to the first endpart, the heat absorption part being provided in contact with theelectromagnet, and the heat dissipation part being derived to an outsideof the vacuum chamber.
 2. The vapor deposition apparatus according toclaim 1, wherein the heat pipe comprises a vapor pipe connected betweenan end part of the heat absorption part and an end part of the heatdissipation part, and a connection pipe connected between another endpart of the heat absorption part and another end part of the heatdissipation part to be formed as a loop-type heat pipe.
 3. The vapordeposition apparatus according to claim 2, wherein the heat absorptionpart of the loop-type heat pipe comprises a plurality of wick structuresarranged horizontally side by side to be formed in a plate-shaped form.4. The vapor deposition apparatus according to claim 3, wherein the eachof the plurality of wick structures comprises a wick core at its centerpart, and a wick is formed in a gear-like shape around the wick core,and grooves are formed between teeth of the wick to provide a path forvapor.
 5. The vapor deposition apparatus according to claim 3, whereinthe heat absorption part of the heat pipe is installed so as to facedirectly a surface facing the deposition mask of the electromagnet andthe substrate for vapor deposition held by the substrate holder.
 6. Thevapor deposition apparatus according to claim 1, wherein theelectromagnet comprises a core, a coil, and a yoke, and the core, thecoil, and the yoke are integrated with each other with a coveringmember, and wherein the heat absorption part of the heat pipe isembedded within the covering member.
 7. The vapor deposition apparatusaccording to claim 6, wherein the covering member comprises aheat-resistant resin.
 8. The vapor deposition apparatus according toclaim 6, wherein the covering member comprises a filler including ametal powder.
 9. The vapor deposition apparatus according to claim 1,wherein the electromagnet comprises a core having a concave portion inone end part of the core, the heat absorption part of the heat pipebeing embedded in the concave portion.
 10. The vapor depositionapparatus according to claim 9, wherein, when a cross-sectional shape ofthe heat pipe is a circular shape having a radius of “r”, across-sectional shape of the core is a circular shape having a radius of“R” and a depth of the concave portion is “d”, where d≥(R²−r²)/2r. 11.The vapor deposition apparatus according to claim 9, wherein a coatinglayer having a thermal conductivity being larger than a thermalconductivity of the core is formed on at least a part of a surface ofthe core and an inner surface of the concave portion, and the heatabsorption part is bonded within the concave portion using an adhesivehaving a thermal conductivity being larger than the thermal conductivityof the core.
 12. The vapor deposition apparatus according to claim 1,wherein the electromagnet comprises a core, the heat pipe has across-sectional area being smaller than a cross-sectional area of thecore, and two or more of heat absorption parts each being the heatabsorption part are embedded in the core.
 13. The vapor depositionapparatus according to claim 9, wherein a resin containing fineparticles having a thermal conductivity being larger than a thermalconductivity of the resin is filled in a gap between the heat pipe andthe core.
 14. The vapor deposition apparatus according to claim 9,wherein the core comprises a powder magnetic core that is formed by aniron powder sintered and pressurized.
 15. The vapor deposition apparatusaccording to claim 1, wherein the heat pipe is formed of a flexiblematerial.
 16. A method of manufacturing an organic EL display apparatus,comprising: forming a support substrate having at least a TFT and afirst electrode; forming an organic deposition layer by depositingorganic materials on the support substrate using the vapor depositionapparatus according to claim 1; and forming a second electrode on theorganic deposition layer.